Pyridazone derivatives

ABSTRACT

COMPOUNDS OF FORMULA:   1-(3-F3C-PHENYL),4-(R1-N(-R2)-),5-X,6-(O=)-1,6-DIHYDRO   PYRIDAZINE   IN WHICH X SIGNIFIES CHLORINE OR BROMINE, R1 SIGNIFIES HYDROGEN OR METHYL AND R2 SIGNIFIES METHYL OR, WHEN R1 SIGNIFIES HYDROGEN, R2 MAY ALSO SIGNIFY ETHYL, ARE DISCLOSED AS POSSESSING SELECTIVE HERBICIDAL ACTIVITY IN COTTON AND CARROTS.

United States Patent r 3,644,355 PYRIDAZONE DERIVATIVES Cuno Ebner, Reinach, and Max Schuler, Arlesheim, Basel-Land, Switzerland, assignors to Sandoz Ltd., Basel, Switzerland No Drawing. Continuation-impart of application Ser. No. 691,249, Dec. 18, 1967. This application Dec. 4, 1969, Ser. No. 882,294

Int. Cl. C07d 51/04 US. Cl. 260-250 A 7 Claims ABSTRACT OF THE DISCLOSURE Compounds of formula:

in which X signifies chlorine or bromine, R signifies hydrogen or methyl and R signifies methyl or, when R signifies hydrogen, R may also signify ethyl, are disclosed as-possessing selective herbicidal activity in cotton and carrots.

This application is a continuation-in-part of application Ser. No. 691,249, filed Dec. 18, 1967, now abandoned.

This invention relates to new pyridazone derivatives which are pre-emergence herbicides, and to their preparation.

The present invention provides compounds of Formula in which X signifies a chlorine or bromine atom,

R signifies a hydrogen atom or a methyl radical, and

R signifies a methyl radical or, when R signifies a hydrogen atom,

R may also signify an ethyl radical.

In accordance with the invention the compounds of Formula I are obtained by reacting a compound of Formula II,

or I

in which X has the above significance, with a compound of Formula III,

2 III in which R and R have the above significance.

The reaction is suitably carried out in a solvent which is inert under the reaction conditions at a temperature from 20 to 120 (3., preferably 70 to 90 C. In a preferred embodiment, a compound of Formula II is heated to 3,644,355 Patented Feb. 22, 1972 ice As starting materials of Formula II are used, e.g.

1-( 3-trifluorornethylphenyl)-4,5-dichloropyridazone-( 6) and 1-(3-trifluoromethylphenyl)-4,5-dibromopyridazone-(6).

The compounds of Formula 11 may be obtained as follows:

3-trifluoromethyl-phenylhydrazine is reacted with an acid of Formula IV,

XX IV in which X has the above significance, preferably at room temperature in the presence of a solvent, e.g. a mineral acid aqueous solution, or an aqueous or anhydrous inert organic solvent, e.g. ethanol, which is evaporated after the reaction is terminated, to give the corresponding dihalogeno acid semicarbazone and this, without isolation, is cyclized by boiling in glacial acetic acid and/ or acetic anhydride or by heating in an aqueous mineral acid, e.g. hydrochloric acid, at a temperature of 70 to about 100 C., or by stirring in a concentrated mineral acid, e.g. sulphuric acid, at room temperature, to give the corresponding compound of Formula II.

A preferred compound of Formula I is l-(3-trifiuoromethylphenyl)-4-dimethylamino-S-chloropyridazone- (6) The compounds of Formula I are useful because they have plant growth control properties. In particular the compounds of Formula I are useful as selective pre-emergence herbicides in the culturing of cotton and carrots, i.e., they are used before emergence of the weeds.

The compounds of Formula I can be applied to the abovementioned uses in admixture with an agriculturally acceptable diluent, carrier or adjuvant. The compounds of Formula I can be applied to the desired locus using conventional applicator equipment. Accordingly, formulations containing a compound of Formula I comprise: spraying agents, e.g. water-dispersible concentrates and wettable powders, dusting agents and granulates, and may be prepared and where necessary after dilution applied to provide the effect desired.

The wettable powder can contain between about 10 and 95 and preferably between 50 and by weight of the compound of Formula I together with one or more wetting or dispersing agents, e.g. an alkyl-benzenesulphonate salt, an alcohol sulphate, a fatty acid ester of sodium isethionate, a sodium N-alkyl-N-aceyl-laurate, sulphonated lignin derivatives, or a liquid polyglycol ether derived from a high molecular weight alcohol, mercaptan or alkylphenol and an alkylene oxide, and a finely divided solid diluent, e.g. talc, diatomaceous earth, kaolin, attapulgite, hydrated silica, synthetic silicates, calcium carbonates (chalk), cellulose derivatives etc. The wettable powder may also contain one or more adhesives, e.g. dextrin, and one or more protective colloids, e.g. ammonium caseinate. The components of the wettable powder may be ground together to form a fine homogeneous mixture.

The water-dispersible concentrate can contain from 20 to 50% and preferably from 30 to 40% by weight of the compound of Formula I together with a dispersing agent; for example a condensation product of naphthalenesulphoniqa id w th d y een lky p nol polyglya col ether or a sulphonated lignin derivative, e.g. calcium lignin sulphonate, a suspending agent, e.g. bentonite, and water The components of the water-dispersible concentrate may be ground together to form afine homogeneous mixture.

The compounds of Formula I are applied to the desired locus e.g. in the form of a dusting agent, a granulate or a spraymg agent.

The composition of the formulation and the percentage of the compound of Formula I therein to be applied to a locus will vary with the manner in which the composition is to be applied. However the concentration of the compound of Formula I in the formulation to be applied to a locus in general is between about 0.01 and 20% and preferably between 0.01 and by Weight of the composition.

The dusting agent for use in application to a locus can contain a compound of Formula I together with a solid carrier or diluent, e.g. talc, diatomaceous earth, kaolin,

bentonite, or calcium carbonate. The dusting agent may be made by mixing or milling together the compound of Formula I and the solid carrier or diluent, or may be made by impregnating the carrier with a solution of the compound of Formula I in a volatile solvent.

The spraying agent, for use in application to a locus, can be a water-dispersible concentrate or wettable powder diluted with a suitable liquid diluent, e.g. water.

The granulate can be made, for example by spraying a solution of the required quantity of a. compound of Fora mula I in a volatile solvent onto an absorbent granular material and subsequently evaporating the volatile solvent, or by mixing the required amount of the compound of Formula I with a powdery carrier optionally together with a surfactant and/or binder and subsequently granulating the mixture by a standard method.

The compounds of Formula I are used, for example, by Working a composition such as described above into the surface of the soil before the plants or the seeds of the crop, e.g. cotton or carrots, are planted (pre-plant incorporated and pre-seed incorporated respectively). Alternatively a spraying composition containing a compound of Formula I is sprayed onto the surface of the soil before the plants or the seeds of the crop, e.g. cotton or carrots, are planted (pre-plant surface spray and pre-seed surface spray respectively) or a spraying composition is sprayed onto the surface of the soil after the seeds of the crop are planted and before emergence of the crop (pre-emergence surface spray). Alternatively the compound of Formula I is applied, for example in the form of a spraying agent, to the soil around established crops, e.g. cotton. All the above methods of using the compounds of Formula I should be carried out prior to or at the latest during the emergence of the weeds from which it is desired to protect the crop. It is preferred to use a technique in which a compound of Formula I is incorporated into the surface of the soil.

The method of application and the dosage of the compound of Formula I used will vary with the crop, with the weeds it is desired to kill, and with the type of soil on which the crop is to be grown. Thus a suitable dosage is generally from about 1 to 12 and preferably from about 2 to 4 lbs. per acre. In general the lower the proportion of organic matter in the soil the lower will be the requisite dosage and conversel the higher the proportion of organic matter in the soil, the higher will be the requisite dosage.

In the following non-limitative examples all the temperatures are indicated in degrees centigrade.

EXAMPLE 1 1- 3-trifluoromethylphenyl) -4-methylamino-5- chloro-pyridazone- 6) g. of l-(3-trifluoromethylphenyl)-4,5-dichloropyrid- Precipitation with. water is then effected, the precipitate is filtered off and dried. 17 g. of 1-(3-trifluoromethylphenyl) -4-methylamino-5-chloropyridazone-(6), having a M.P.

let 183-185, are obtained by recrystallization from alco- The l-(3 trifiuoromethylphenyl) 4,5 'dichloropyridazone-(6) used as starting material may be produced as follows:

57.5 g. of mucochloric acid are dissolved in cc. of absolute alcohol and 60 g. of m-trifluoromethylphenylhydrazine are added thereto. The solution is then evaporated to dryness at reduced pressure and heated for 40 minutes under reflux with the addition of cc. of glacial acetic acid and 120 cc. of acetic acid anhydride. Subsequently evaporation to dryness at reduced pressure is again effected, whereupon, after recrystallizing from 90% aqueous alcohol colourless crystals having a M.P. of 92- 94 are obtained. The yield of l-(3-trifluoromethylphenyl)-4,5-dichloropyridazone(6) amounts to 94 g.

EXAMPLE 2 l- 3-trifiuoromethylphenyl -4-ethylamino-5- chloropyridazone-(6) 20 g. of 1-(3-trifluoromethylphenyl)-4,5-dichloropyridazone-(6) and 20 g. of ethylamine in 200* cc. of alcohol are heated to 85 for 24 hours. Precipitation with water is then effected, the precipitate is filtered off and dried. 17 g. of 1-(3-trifluoromethylphenyl)-4-ethylamino 5-chloropyridazone-(G), having a M.P. of 132, are obtained by recrystallization from alcohol.

EXAMPLE 3 1-( 3-trifiuoromethylphenyl) -4-dimethylamino-5- chloropyridazone-(6) A solution of 36.5 g. of dimethylamine in 200 cc. of alcohol is added to 50 g. of 1-(3-trifiuoromethylphenyl)- 4,5-dichloropyridazone-(6) and stirring for 24 hours at 85 is effected. Precipitation with water is carried out, the precipitate is filtered off and dried. By recrystallization from alcohol there are obtained 46- g. of 1-(3-trifiuoromethylphenyl)4dimethylamino-S-chloropyridazone (6) having a M.P. of 153.

EXAMPLE 4 1- 3-trifluoromethylphenyl) -4-methylamino-5- bromopyridazone- 6) 10 g. of l-(3-trifluoromethylphenyl)-4,5-dibromopyrid azone-(6) and 4 g. of methylamine in 50 cc. of alcohol are heated to 85 for 24 hours. By the same working up as in the above examples 5.8 g. of 1-(3-trifluorornethylphenyl)-4-methylamino-S-bromopyridazone-(6), having a M.P. of 156-158", are obtained.

The 1-(3-trifluoromethylphenyl) 4,5 dibromopyridazone-(6) used as starting material may be produced as follows:

100 g. of mucobromic acid are dissolved in 200 cc. of absolute alcohol and 62 g. of m-trifiuorornethylphenylhydrazine are added thereto. The solution is then evaporated to dryness at reduced pressure and heated for 4 hours under reflux with the addition of cc. of glacial acetic acid and 130 cc. of acetic acid anhydride. Subsequently evaporation to dryness at reduced pressure is again effected, whereupon, after recrystallizing from 90% aqueous alcohol crystals having a M.P. of 103-105 are obtained. The yield of 1-(3-trifluoromethylpheny1)-4,5-dibromopyridazone-(6) amounts to 104 g.

EXAMPLE 5 1- 3-trifiuoromethylph'enyl) -4-ethylamino- S-bromopyridazone- (6) phenyl) 4 ethylamino 5 bromopyridazone (6), having a M.P. of 138-140", are obtained after recrystallization from alcohol.

EXAMPLE 6 1- 3 -trifluoromethylphenyl) -4-dimethylamino- 5-bromopyridazone-(6) 25.8 g. of 1 (3 trifluoromethylphenyl) 4,5 dibromopyridazone-(6) and 30 g. of dimethylamine in 200 cc. of alcohol are heated for 24 hours to 85. By the same Working up as in the above examples 20 g. of 1-(3-trifluoromethylphenyl) 4 dimethylamino 5 bromopyridazone-(6), having a MP. of 159, are obtained.

In the following examples (a) to (f) the production of herbicidal preparations is described.

(a) 70 g. of 1 (3 trifluoromethylphenyl) 4 dimethylamino 5 chloropyridazone-(6) together with 29 g. of an inert solid carrier consisting of a mixture of 15 g. of kaolin, 7 g. of diatomaceous earth and 7 g. of talc, and 1 g. of an adhesive are ground to a fine powder in a ball mill; the resulting powder serves as dustin-g agent.

(b) 80 g. of 1 (3 trifluoromethylphenyl) 4 methylamino 5 bromopyridazone-(6), 5 g. of calcium lignin sulphonate powder, 5 g. of a pulverulent mixture consisting of three-quarters soybean albumin extract (spray soy) and one-quarter dextrin, and 10 g. of colloidal silicic acid are finely ground in a ball mill together with 200 cc. of water.

When the suspension obtained in accordance with (e), without the addition of thickening agent, is carefully evaporated to dryness in a vacuum and subsequently ground in a ball mill, a fine loose spraying powder is obtained which, on stirring into water in an amount to give an active agent concentration of 80%, gives liquid preparations having excellent suspension properties.

(d) A solution in acetone of 20 g. of 1-(3-trifluoromethylphenyl) 4 dimethylamino--chloro-pyridazone- (6) is sprayed onto 180 g. of pumice granulate of grain size from 0.3 to 1 mm.; the solvent is then removed in the vacuum of a water pump at 40-60. A grainy granulate with excellent flow properties results.

(e) Water-dispersi ble concentrate: 40 g. of 1 (3 trifluoromethylphenyl) 4 dimethylamino 5 chloropyridazone-(6) together with 15 g. of calcium lignin sulphonate powder, 1 g. of bentonite and 44 g. of water are ground in a ball mill to a particle size of the order of 5 microns or less. The resultant aqueous suspension concentrate has a good storage stability and may easily be diluted with water to give stable suspensions which can be used as herbicidal spray liquors.

(f) 80% Wettable powder: 820 g. of 1 (3 trifluoromethylphenyl) 4 dimethylamino 5 chloropyridazone- (6) are ground in a pin disc mill to give a powder of fineness of at least 90% 45 microns; this fine powder is put into a horizontal mixer in which mixing is effected for about 2 hours with 180 g. of a mixture consisting of g. of sodium dodecyl benzene sulfonate, g. of a partially desulfonated purified sodium lignosulfate and 155 g. of kaolin. The resulting mixture is finely ground in a pin disc mill. A spraying powder with 80% by weight active agent content is obtained; this material is suspendible in water with great ease.

The compounds of Formula I have a damaging effect on the following weed species when applied before the sowing of seeds of these weeds.

Alopecurus pratensis Amaranthas retroflexus Chenopodium album Plantago major Serzecio vulgaris Cenchrus echinatus Digitarz'a sanguinalis Echinochloa cruspavonis Dioscorea sp.

Chenopodium murale Amarantus caudatus Amarantus spinosus Portulaca oleracea Adonis dentata Gynandropsis pentaphylla Alopecurus myosuroides Cakile maritima Capsella bursa-pastoris Diplotaxis harra Capsella bursa pastoris Echinochloa crus-galli Poa trivialis Stellaria media Sisymbrium irio Calopogonium sp. Euphorbia peplus Euphorbia prunifolia Ipomoea sp.

Datura sp.

Solanum nigrum Acanthospermtma hispidum Ageratum conyzaides Anthemis sp.

Anacyclus alexandrinus Atractylis flava Bidens pilosa The compounds of Formula I are not toxic to Daucus carota or to Gossypium herbaceum at dosages at which they damage. weeds.

What is claimed is:

1. A compound of formula:

in which X signifies chlorine or bromine,

'R signifies hydrogen or methyl and R signifies methyl or when R signifies hydrogen, R may also signify ethyl.

2. A compound according to claim 1, which is 1-(3- trifluoromethylphenyl) 4 dimethylamino 5 chloropyridazone- 6) 3. A compound according to claim 1, which is 1-(3- trifluoromethylphenyl) 4 ethylamino 5 chloropyridazone- (6 4. A compound according to claim 1, which is 1-(3- trifluoromethylphenyl) 4 methylamino 5 chloropyridazone- 6) 5. A compound according to claim 1, which is 1-(3- trifluoromethylphenyl) 4 methylamino 5 bromopyridazone- 6) 6. A compound according to claim 1, which is 1-(3- trifluoromethylphenyl) 4 ethylamino 5 bromopyridazone-(fi).

7. A compound according to claim 1, which is 1-(3- trifluoromethylphenyl) 4 dimethylamino 5 bromopyridazone- 6) References Cited UNITED STATES PATENTS 3,222,159 12/1965 Reichneder et al. 260-2504 OTHER REFERENCES Yale, Jour. of Med. & Pharma. Chem. vol. No. 2 (1959) pp. 121-133.

NICHOLAS S. RIZZO, Primary Examiner US. Cl. X.R. 719Z 

